This invention is related to a co-pending Olin S. Lutes application, Ser. No. 677,181 filed Apr. 15, 1976 entitled "Magnetic Thin Film Plated Wire Switch" and a Lutes et al U.S. Pat. No. 3,902,167, issued Aug. 26, 1975, entitled "Magnetic Thin Film Switch", both assigned to the same assignee as the present invention.
Those references are directed to a magnetic film plated wire switch. The switching element is a wire substrate which is coated with a low or zero magnetostrictive anisotropic magnetic thin film electro-deposited or electroless deposited. In the undisturbed state the magnetization of the magnetic film has a component along the wire axis. Actuator means applies an external magnetic film having a component along the axis of the wire which is sufficient to change the state of the magnetic switching element. Ouput means sense the state of the magnetic switching element.
In the instant invention, a negative magnetostriction thin-film plated wire magnetic switch is described in which the wire is tensioned to control or adjust the switching threshold level of the wire as a function of the tension applied. The present invention fills the need for an adjustable threshold on-off magnetically actuated switch which can be actuated by a relatively small external magnetic field even though applied at an arbitrarily slow rate.